INDIANAPOLIS -- Kentucky forward Willie Cauley-Stein, the nation's fifth-leading shot blocker during the regular season, is unlikely to play in Sunday's Elite Eight battle with Michigan.

Coach John Calipari described Cauley-Stein as "doubtful" for the Midwest Regional final as a result of an ankle injury suffered Friday against Louisville.

"I will tell you, he's still in a (walking) boot," Calipari said. "He's doubtful. He's acting like he thinks he can do something, and I would be stunned if he played in this game.

Cauley-Stein entered Friday's 74-69 win over Louisville averaging 7.0 points, 6.2 rebounds and 2.9 blocks per game this season. He posted 101 blocks in 24.3 minutes per game in the regular season.

The 7-footer injured his left ankle after playing 4 minutes on Friday. He limped into the locker room after the injury and was on crutches after the game.

"He's saying that he may want to give it a try (against Michigan)," Calipari said. "But he hasn't been out of that boot."

Kentucky announced at halftime Friday that Cauley-Stein would not return to the game and CBS sideline reporter Tracy Wolfson said she heard Cauley-Stein tell trainers, “I heard it pop."

"We've got to prepare if Willie doesn't prepare, which means we've got to tweak our offense a little bit," Calipari said. "We've got to tweak our defense a little bit. He may not be in the game. Hopefully he's able to limp his way in there and give us a few minutes, but maybe he can't."

The report of Cauley-Stein saying he heard a pop immediately led to speculation that he tore his ACL. Calipari clarified, though, that it's an ankle injury.

Second-seeded Michigan (28-8) and No. 8 seed Kentucky (27-10) will meet Sunday at 5:05 p.m. at Lucas Oil Stadium for trip to the 2014 Final Four.

Brendan F. Quinn covers University of Michigan basketball. Follow him on Twitter for the latest on Wolverines hoops. He can be contacted at bquinn@mlive.com